1. Field of the Invention
The present invention relates to a dual input power supply, and more particularly to a dual input power supply having an integrated magnetic element.
2. Description of the Related Art
Common electronic devices, such as notebook computer, PDA, and mobile phone, need an AC-to-DC converter to provide the DC power required for the operation of these electronic devices. Typically, in addition to built-in batteries, the AC-to-DC converter is another important power source for these electronic devices.
Recently, the demand for electronic products with high efficiency and low power consumption is gradually increased. It has become an important factor that how to provide these products with a steady power supply and maintain a minimum power consumption. With advancement in semiconductor technology, semiconductor devices, such as MOSFETs, are also increasingly utilized in co-frequency rectifying power devices. As to current products in the market, many co-frequency rectifying driving ICs are available for directly being utilized in power supplying devices. However, these products have a high price and need a complicated control way it is hard to accept them in the market.
U.S. Pat. No. 6,650,560 discloses a programmable dual input AC and DC power supply utilizing a single-loop optical feedback, the dual input AC and DC power supply comprises: a dual input, having a first input and a second input; a connector; a power converter circuit, comprising an AC-to-DC converter, a DC-to-DC booster converter, a filter circuit, a feedback circuit, and a buck converter; and an output, having a first output and a second output. The connector is used for connecting the input powers having different power signals from the first input and the second input. Different cores are used in the connector to connect different power signal inputs. In such a connection way, many complicated components are required, and occupying a large space in the power supply.
Furthermore, with reference to FIG. 4, a DC-to-DC booster converter for a conventional dual input power supply is shown. The conventional DC-to-DC booster converter uses a MOSFET 15 as a synchronous rectifying device. The MOSFET 15 has a body diode 13 such that it is not possible to completely dis-conduct the MOSFET 15, and thus the input can not be isolated from the output and the function of protection is not achieved. The above drawbacks need to be overcome and resolved.